Ensuring the copy protection of digital data

ABSTRACT

When digital data is to be copy protected at a processing station, for example, prior to its encoding and recording onto an optical disc, it is necessary to control a compliant encoder to utilise copy protection files to perform the copy protection routine. To ensure that the digital data is reliably copy protected, predetermined noise signals are incorporated into the digital data and the processing steps which add the copy protection are additionally caused to remove the noise signals. By this means, if the digital data is not copy protected, the noise signals remain. This enables non-copy protected digital data to be readily identified and ensures that it is effectively unusable to a consumer.

CLAIM OF PRIORITY

This application is divisional of U.S. application Ser. No. 10/202,132filed Jul. 24, 2002 which is incorporated herein by reference.

DESCRIPTION

The present invention relates to a method of ensuring digital data iscopy protected and to media produced by the method and to files forproducing the method.

More and more data is being provided on optical discs such as CDs andDVDs. However, burners or other recording devices for copying opticaldiscs are becoming available to the consumer such that there is a evergrowing need to protect the digital data recorded thereon againstcopying. Numerous copy protection techniques have been proposed and,increasingly, publishers of digital data require that the copies issuedto the public are copy protected by appropriate techniques.

However, the mastering houses which produce CDs and DVDs will produceboth copy protected discs and discs without copy protection. Theencoders used in the mastering houses do not, for example, incorporatewithin them the ability to detect which input data requires copyprotection and then to automatically copy protect that input dataidentified. This means that the possibility exists that input data willbe incorrectly encoded onto an optical disc without copy protection suchthat the data is made available for copying.

The present invention has identified that there is a problem in ensuringthat digital data encoded onto an optical disc is copy protected andproposes solutions.

According to the present invention there is provided a method ofensuring digital data is copy protected, the method comprising the stepsof:

delivering input data to a processing station; and

subjecting the input data at the processing station to one or moreprocessing steps such that processed digital data is output, wherein atleast one of the processing steps is a step to add copy protection;wherein

the input data at the processing station has had predetermined noisesignals incorporated therein; and wherein

the method further comprises the step of arranging that the processingstep or steps adding the copy protection cause the removal of saidpredetermined noise signals.

With embodiments of a method of the invention, the input data at aprocessing station has had noise added thereto. If, during processing ofthat input data at the processing station, copy protection is added, thecopy protection processes cause the added noise to be removed. Thus, thedigital data output is copy protected digital data from which the addednoise has been removed. However, if, for example, through human failure,the input data is not subject to a copy protection technique, the noisesignals will not be removed. These added noise signals will thereforeappear in the processed digital data output from the processing station.

It can be chosen whether the noise is to be incorporated, for example,just at the beginning of the input data. In this case, those checkingthe data output can be quickly and easily alerted to the fact that copyprotection has not been added. Alternatively, the predetermined noisesignals may be incorporated throughout the input data so that if thenoise is not removed the resulting digital data output is, in effect,unusable to a consumer.

Preferably, the input data is to be encoded at the processing station,and at least one of the processing steps is a step to encode the data.

Generally, digital data is encoded at the processing station. The inputdata with the incorporated predetermined noise signals may be in eitherdigital or analog form. Where the input data is supplied as analog it isconverted into digital as one of the processing steps.

It is generally intended that the processed digital data output from theprocessing station in accordance with embodiments of the method of theinvention is to be recorded onto a optical disc. However, the method mayfind use where the processed digital data is to be copy protected forrecording on other media or is to be used in other situations.

Preferably, the method further comprises the step of reading or playingthe processed digital data output from the processing station to checkthat the predetermined noise signals have been removed.

The predetermined noise signals can be chosen, for example, so that theyare at locations in the digital data output which are readilyaccessible. For example, it may be arranged that the noise is present atthe start of a music track on an audio CD. This means that the outputfrom the processing station can be quickly checked. In this respect, thepresence of the predetermined noise signals indicates that no copyprotection has been added to the encoded data and/or that the copyprotection technique has failed, whilst the absence of such noisereveals that appropriate copy protection has been provided.

A publisher or compiler of data who provides input data to a masteringhouse, for example, can ensure that the input data is subject to copyprotection by incorporating the predetermined noise signals to the inputdata before it is delivered to the mastering house. The input data withthe predetermined noise signals may be delivered to the processingstation recorded on an optical disc, on a tape, or on any other recordcarrier.

Additionally and/or alternatively a method of the invention furthercomprises the step of adding the predetermined noise signals to theinput data at the processing station before said one or more processingsteps are undertaken.

In this alternative, the noise signals are added to the input data as itis prepared for further processing at the processing station. Where thedata is to be encoded for application to an optical disc, for example,the addition of the predetermined noise signals is undertaken before theencoding and other processing steps.

The added predetermined noise signals can be chosen as required and asis appropriate to the nature of the data. For example, erroneous values,which cause noise spikes, may be added into the input data in thedigital domain at preselected locations. For audio data, for example,such erroneous values correspond to impulses superimposed onto theanalog audio data and, if played, produce audible clicks. Additionallyand/or alternatively, impulses may be superimposed onto the input datain the analog domain at preselected locations. Such “spikes” in theinput data are readily discernible in any domain. This is important bothfor the checking of the digital data output from the processing station,but also in ensuring that the added noise signals are reliably andaccurately removed.

The predetermined noise signals can be removed by providing, forexample, at the processing station, details of the noise signals whichhave been added. For example, the locations of predetermined noisesignals may be identified and the method may comprise the step ofremoving or restoring data at each identified location.

Where the added noise is, for example, erroneous values in the digitaldomain and/or impulses added in the analog domain, the step of removingthe noise may comprise detecting the added noise by detecting erroneousvalues and/or impulses in the input data and identifying the locationsat which the noise occurred, and removing or restoring the data at eachidentified location.

The detection of the added noise and the restoration of the input datamay be done, for example, by looking at the values of the data anddetermining a more appropriate value, and/or an audio detector may beused which reacts to “clicks”, and/or a visual detector may be providedto display the data such that any impulses are visible. The process maybe performed automatically and/or under the intervention of an operator.What is required, of course, is that the added noise can be identifiedand removed quickly and easily and the appropriate values restored. Inmost cases this will be done by providing to processing means at theprocessing station details of the noise which has been added and itslocation. This information can be provided together with the copyprotection information so that the removal of the noise and the additionof the copy protection is mutually dependent.

As set out above, the primary function of the added noise signals is toprovide discernible noise if the copy protection processing has not beenperformed or completed. However, it is additionally possible to ensurethat the noise signals as added additionally carry information. Thus,the added noise signals are arranged not to be random but, to be codedand, for example, could identify the type of copy protection requiredand/or for any other purpose.

Where the input data is audio, the added noise signals will be audibleeither to the human ear or to a machine.

The present invention is not limited to the type of copy protectionwhich is used and that will be chosen, for example, to be appropriate tothe nature of the input data. For digital audio compact discs (CD-DA)schemes such as those described in, for example, WO 01/15028 and GBApplication No. 0116278.3 may be utilised. Furthermore, althoughcurrently the copy protection files to prepare the input data forencoding are provided at the processing station, it would be possiblefor copy protection files to be added to the input data by the publisheror compiler.

The present invention also extends to apparatus for copy protectinginput data comprising a processing station arranged to receive inputdata and to output processed digital data, said apparatus being arrangedto perform a method as defined above.

According to a further aspect of the present invention, there isprovided an executable application file arranged to ensure digital datais copy protected, the application file comprising:

an instruction to replace data values at preselected locations in inputdata during processing of the input data to add copy protection, and

an instruction to output the processed data in digital form.

In an embodiment, the executable application file further comprises aninstruction to detect the data values to replace by determining theexistence of data values in locations which should be absent of datavalues and/or by determining the existence of data values with erroneousvalues.

The present invention also extends to an executable application filearranged to ensure that digital data is copy protected, the applicationfile comprising:

predetermined noise signals for addition to input data,

an instruction to add the predetermined noise signals to input datawhich is to be copy protected, and

an instruction to add the predetermined noise signals at preselectedlocations.

According to the invention, there is also provided a data carriercarrying encoded digital data for recording on an optical master disc,the digital data having been processed by a method as defined above,and/or having been processed using an executable application file asdefined above.

Embodiments of the present invention will hereinafter be described, byway of example, with reference to the accompanying drawings, in which:

FIG. 1 shows schematically a process of mastering a CD,

FIG. 2 shows schematically a similar process of that of FIG. 1 but withthe addition of copy protection to the CD.

FIG. 3 shows schematically a method of the invention for ensuring thatthe audio content of the CD is copy protected,

FIG. 4 shows a further schematic embodiment of a method of theinvention, and

FIG. 5 illustrates how noise signals can be utilised to carryinformation.

The embodiments of the invention described and illustrated herein aredescribed with specific reference to the manufacture of digital audiocompact discs (CD-DA). However, the methods described herein are notlimited to the recording of audio data onto a CD and may be utilised,for example, to ensure that any digital data recorded onto an opticaldisc is copy protected.

FIG. 1 indicates schematically the mastering of a CD-DA at a masteringhouse. As is well known, a publisher or compiler provides input data 2which is to form the audio content of a CD master. This input data 2 maybe, for example, analog recordings on tape or on disc, or may be digitalaudio data similarly provided on tape or disc. If the input data 2 isanalog it is converted into digital as an initial stage of theprocessing.

Any initial processing, such as analog to digital conversion, isundertaken at a preparatory stage 4 of a processing station 10. Inaddition, files 5 in accordance with an agreed Disc Description Protocol(DDP) are provided to prepare the input data 2 for encoding. Thereafter,prepared input data is applied to an encoder 6 where it is encoded andthen output as processed digital output data 8. The output data 8 ispreferably output on a master tape or disc which will be used to producethe CD master.

FIG. 2 shows an alternative method to that of FIG. 1 arranged to copyprotect the processed output data 8. In this embodiment, copy protectionfiles 12 are utilised to prepare the input data for encoding togetherwith the DDP files 5.

In this case, if the prepared data from the preparatory stage 4 is inputto a compliant encoder 6, the resulting processed output digital data 8will be copy protected.

As an alternative, which is not illustrated, the copy protection files12 may be provided with the input data 2, for example, by the publisheror compiler.

In this respect, DDP files as 5 do not incorporate any agreed protocolfor copy protection. A standard encoder, as 6, will not look for, andutilise, copy protection files 12 even where they are provided. Toinitiate copy protection requires both copy protection files 12 and acompliant encoder controlled to perform the copy protection routine.

At present, there is the problem that human intervention is required toidentify input data 2 which is to be copy protected and then to ensurethat the encoder 6 is controlled to perform a copy protection routineusing the copy protection files 12 in the preparation of the data 2.Furthermore, if copy protection data is not added to the input dataduring its preparation for encoding, the input data 2 will be encodedand output at 8 without the required copy protection. As the processeddigital data output will be perfect, perfect and copyable CDs willresult from the mastering process.

FIG. 3 illustrates schematically one method of the present invention toensure that the CD-DAs are copy protected. In the embodiment shown inFIG. 3, the input data 2 which is to be presented to a processingstation 10 has had predetermined noise signals, as indicated at 14,added thereto. These noise signals 14 may be added to the original inputdata 2 in the analog or the digital domain. The noise signals 14 arearranged to act as markers to ensure that copy protection isappropriately applied. Accordingly, at the processing station 10, theinput data 2, with the added noise signals 14, is subject to preparationunder the control of DDP files 5 and is also subject to copy protectionunder the control of the copy protection files 12. However, the copyprotection files 12 are modified such that the copy protection processremoves the added noise. Accordingly, it will be appreciated that theprocessed digital data 8 output from the processing station 10 will, ifit has been copy protected, be free from the added noise. However, ifthe copy protection process has failed, for example, because the encoder6 did not recognise and act on the copy protection files 12, theprocessed digital data 8 output will still incorporate the noise signals14. The existence of the noise can be readily detected either by humanear, or eye, or by detection means.

FIG. 4 shows an alternative embodiment in which the input data 2 isprovided to the processing station 10 without the addition of noise. Inthis embodiment, means are included in the preparatory stage 4 to addnoise signals 14 to the input data 2. Thereafter, the input data isprepared under the control of the DPP files 5 and the copy protectionfiles 12. The preparation is to be controlled such the noise signals 14are detected and removed as copy protection is added to the input dataunder the control of the copy protection files 12. Of course, and aspreviously, this requires that the encoding takes place by way of acompliant encoder 6A.

In the embodiment shown in FIG. 4, the processing station 10 is shown tohave four separate encoders 6, labelled A, B, C and D. Only the Aencoder is, in this embodiment, compliant with the copy protectiontechniques. It is therefore required that any input data 2 which is tobe copy protected is fed for encoding to the A encoder 6. This can beachieved by an automatic process arranged to be performed at thepreparatory stage 4 in which the existence of any added noise, as 14, isdetected. Where there is added noise, the input data 2 is prepared withthe copy protection files 12 and then directed to the compliant Aencoder 6.

Additionally and/or alternatively, the presence of added noise may bedetected by an operator and used to cause the addition of copyprotection files and then the use of the correct compliant encoder 6A.

The nature and format of the added noise can be chosen as required. Foraudio applications it is particularly useful to add to the digital inputdata, erroneous values which cause noise spikes in the analog domain.These additions of spikes are made at preselected locations. Sucherroneous values correspond to impulses superimposed on the analog audiodata and, if played, produce audible clicks. The added noise spikes inthe input data are readily discernible in any domain.

In one embodiment of a method of the invention, for an audio CD, it isproposed to add spikes, that is, audible erroneous values, before thecommencement of the first audio track.

From the above, it will be appreciated that if the spikes are added tothe audio data, but the data escapes the application of copy protectionbefore it is encoded, the output digital data 8 will similarly havespikes at the commencement of the audio track. The existence of suchspikes can readily be determined, for example, by looking at the outputdata on a display, and/or by listening to the output when the audibleclicks will be apparent. Alternatively, automatic detection is possible.However made, a check of the processed data at the output 8 will quicklyreveal when the required copy protection has not been incorporated.

It would be possible to incorporate added noise signals throughout theinput data 2 so that any data which is processed, but without beingsubject to copy protection will produce a very poor recording on theresultant CD. However, at present, it is thought that it will besufficient to add noise signals at a few well chosen locations. Makingrelatively few additions of spikes has the advantages that it reducesthe effort necessary to remove the noise during the addition of copyprotection and enables the process to be undertaken without there beingany need to alter the underlying audio data in any way.

It will be appreciated that the addition of noise signals, for example,as specific erroneous values can be used to carry information. FIG. 5illustrates, logic values which might be accorded to digital dataamplitudes. The erroneous values illustrated, for example, may be thenoise signals added at the commencement of an audio track. It will beseen that these samples can be used to represent the values 4704. Byadding noise signals representing values in this manner, it is possibleto tag the input data 2 with information which may be used for anypurpose.

It will be appreciated that variations in and modifications to theembodiments as described and illustrated may be made within the scope ofthis application as defined in the appended claims.

1.-25. (canceled)
 26. A method of ensuring data is copy protected, themethod comprising: receiving input data at a processor, the input dataincluding a watermark at a pre-selected location; modifying a copyprotection process to enable the removal of the watermark; and applyingthe modified copy protection process to the input data thereby bothremoving the watermark and copy protecting the input data.
 27. Themethod of claim 26, further including encoding the input data.
 28. Themethod of claim 27, wherein the input data is digital data which is thenencoded at the processor.
 29. The method claim 27, wherein the inputdata is in analog form, which is then converted into digital data andencoded.
 30. The method of claim 26, wherein processed data output fromthe processor is to be recorded onto an optical disc.
 31. The method ofclaim 26 further comprising reading or presenting processed data outputfrom the processor to determine if the watermark has been removed. 32.The method of claim 26, wherein the watermark has been incorporated inthe input data by a publisher or compiler, the input data with the addedwatermark being delivered subsequently to the processor.
 33. The methodof claim 32, wherein the input data with the watermark is delivered tothe processor as recorded on an optical disc, on a tape, or on any otherdata carrier.
 34. The method of claim 32, wherein processed data outputfrom the processor is to be recorded onto an optical disc.
 35. Themethod of claim 32, further comprising reading or presenting processeddata output from the processor to determine if the watermark has beenremoved.
 36. The method of claim 26, further comprising adding thewatermark to the input data at the processor.
 37. The method of claim36, wherein processed output from the processor is to be recorded ontoan optical disc.
 38. The method of claim 36, further comprising readingor presenting processed data output from the processor to determine ifthe watermark has been removed.
 39. The method of claim 26, furthercomprising removing the watermark and restoring the original data. 40.The method of claim 26, wherein the watermark is added to the input datain the digital domain.
 41. The method of claim 26, wherein the watermarkis added to the input data in the analog domain.
 42. The method of claim40, further comprising detecting and removing the watermark andrestoring the original data.
 43. The method of claim 42 furthercomprising reading or presenting the processed digital data output fromthe processor to determine if the watermark has been removed.
 44. Themethod of claim 42, wherein the watermark has been incorporated in theinput data by a publisher or compiler, the input data with the addedwatermark being delivered subsequently to the processor.
 45. The methodof claim 42, wherein the input data with the watermark is delivered tothe processor as recorded on an optical disc, on a tape, or on any otherdata carrier.
 46. The method of claim 26, wherein the watermark isarranged to carry information.
 47. An apparatus for copy protectinginput data comprising: a processor arranged to receive input data, theinput data including a watermark added into the input data, theprocessor including a copy protection process; a preparatory mechanismto modify the copy protection process to enable the removal of thewatermark; and an encoding mechanism responsive to the preparatorymechanism, wherein the encoding mechanism encodes the input data toproduce processed digital data which is copy protected, wherein themodified copy protection process causes the encoding mechanism to removethe watermark from the processed digital data output.
 48. An apparatusfor copy protecting input data comprising: a processor arranged toreceive input data and to output processed digital data, the processorincluding a watermark generator to add a watermark to the input data,the processor including a copy protection process; a preparatorymechanism to modify the copy protection process to enable the removal ofthe watermark; and an encoding mechanism responsive to the preparatorymechanism, wherein the encoding mechanism encodes the input data toproduce processed digital data which is copy protected, wherein themodified copy protection process causes the encoding mechanism to removethe watermark from the processed digital data output.
 49. A data carriercomprising: encoded digital data for recording on an optical masterdisc, the digital data having been processed from input data, the inputdata including a watermark, the digital data having been processed bymodifying a copy protection process to enable the removal of thewatermark, and applying the modified copy protection process to theinput data thereby both removing the watermark and copy protecting theinput data.
 50. The data carrier of claim 49, wherein the data carrieris an optical disc.